Process of making incandescent lamps.



fill

limit the life of lilililklvF-WCYHZ lamps is a, de

iirzuls R. WHITNEY,

(ll? SGHENECTADY, NEW' YORK,

ASSIGNOB T0 GENERAL ELECTRIC COMTE'AHY, A GOB'PUBATIQN 0 NEW YORK PRUCE-SS OF MAKIKG INGANDESCENT LAMPS.

ll ,ilf ifimlllil.

l 'lo Drawing.

Specification of Lemis mum, implication filed November 27, 1908. Sea'lel. No. 484,551.

Patented May "KL, 1912,

To all/whom it may ccncem: lle it known that l, o, is R. WHITNEY, a Ci'lliien of ihe United States, residin at fichencciedy, county of Schenectady, l ta'te i of New York" have invented certain new and weird Improvemenis in Processes of lvliihing lncendesceni Lumps, of which the l lion.

following is e specific lily 'invenlion relates; to incandescent lmntps and Slfllllil'i articles in which a high vacuum mus? he maintained unchanged l l'h'ro ghouiin: of the lamp, and its obl I to provide a process for securing, in lime than required for the exhaustion of a lamp in lhe nsmil lTlhIiIiQ'ln a very perlfeci vacuum which will remain substantially imchcnged 'lhi-oughoui the life of the lamp.

One of the principal factors tending to e in the viicuun'; caused by the i'adnal. n from the glass walls of t c bulb 01" Water vapor absorbed or och the glass. These gases and the Wohl- I libcii'zlted as the lamp becomes moi and when liberated, either attack ihc filament or, by impeii'ing; the vacuum, cause electrical discharges from the fila-- ine'm'. lliG'f-Pijy caiieing the filai'nent to grad izell'y crumble and reaching in the formation of light sz bsoihing (leposil on the glass walls.

in the process of El'hil'lilffifilllfljllSilall folt l0.l\'l3(l, the bulbs; of lIlQM1(lOH(tPHt lamps are I blown in the glass works; and offer beoon1- l cool are packed in Eill'ilW or other paclo in iimtmiul and shipped to ihe lamp works. ll-elorc he bulbs; are media the lamp works l l they in be washed in remove the dust and (llll. 1; l J1 the interim and during; thia wash im! the glass wells al'isorh 'i'zonsiderzible 1 Wale: which cannoi he entirely removed even by subsequent careful diving in drying furnaces. in the next step the Iflfil'lllffiih mire the bulb is providcd with a, iiibiilaliure "through which l'imlf, exhausted and the stem on which the filumcnl' is mounted is fused into illi noel; of the bulb in the sealicgin rcdi'xi of the factory. -l"lie lamps are then permitted :0 cool and are stored in imys and in lhe course of time are taken to the exhausting pump to be exlimisti'id. It

i l 18 found that While the lamps are in lslsoi'age ihc cold Walls of lhe lamp bulb ibsorb all 1 doe elei'neui's of iitn'loepheric an", especially l m. oi" oi"; water and it is customer" to drive i lamp is 11] use,

out. of the bulb as much of tho occluded and Water vapor as possible by heat-in g lhe lmiips While theyere on the exhausting i mp, but this procedu 'e doesnqt avoid the ifficiilt becaaise he heating cannot be car ried high enough to drive out all of the 00- chided gases or Water-vapor, on account of the tendency of the heated bulbs to collapse as the exhaustion proceeds. Y In carrying out my invention thelamp' which comes fi'om he sealing-in room pnr Tliifll with a tubulature and yeady be be exhausied and sealed off is placed in an oven 01" similar heating device and raised lo a temperature higher than'the temperature attained by the walls of the lamp when the while at the; same time astream of carefully dried gas is passed into and out of: the bulb. The occluded gas and water vapor ai-e driven out of the WallSfdf the bulb by the heating and are carried. away by file stream of dried and heated gas.; It is preferable, though not necessary, to carry the heat to the point at which the walls of the bulb begin to soften, which can he done with safety since the bulb is open to the aimosphere and there is no tendency for the walls of the bulb to, collapse.

Any suihrble gas may be used, but owing to the high temperature attained by the filamen's and the walls of the bulb. it is necessarylo use some inert gas; which will not ltiflQkp ellllii the filament or the glass of the bulb. Yi' licn my inveniimi isused in com noctiim with lamps having easily oxidimble metallic filaments, the best. results are ob tained by using pure hyd 'ogen, which can easily be obtained in o dry slate and which. ellcctually prevents oxidation of the lilaments. It has been found that when hydro gen used end the bulb is made of; glam of the kind commonly used in incondeeiaent lflll'lilfi, the walls of the hi are attacked and a dark coating is formed '1 -lie iempemiigre is carried much above 400" mnizigmde, a very perfect bulb is; heated to kl. temperature of .ebout 400 ccntigrzide, and iii-ct icm mmture is not exceeded when hydl'ogen is passed through the bulb.

H the hill temperature and hydrogeii b has been mein'iained at a high or other inert for a sufiiciena length oif time, it will found that practically all. of the gas and vacuum can be obtained if lhc gas has been passed through the hot bulb while on quired and, since water vapor occluded on the walls of ,the

bulb have been driven off and carried away by the stream of dried gas. The lamp is then ready to be exhausted and is preferably transferred to the exhausting pump while still hot and is maintained atas high a'temperature as is practicable while it is on the exhausting pump, although a temperature of about 300 ccntigrade cannot be exceeoled While the bulb is being exhausted on account of the tendency of the bulb to collapse.

When. the Walls of the bulb have been entirely freed from occluded gas and water vapor as above described and the bulb is fiill of dried hydrogen, the bulb may, if desired, be rendered air tight by scaling in any desired way and can then safely be kept fo considerable length of time before it is put on the exhaust pump, is .no opportunity for air and water vapor to nine occluded by theinner Walls of the bulb. Since the tubulature is quite small and the diffusion of the hydrogen through the tubulature is notvery rapid, the tubulature may be left open, the lamp permitted to cool down to a temperature at which it may be handled easily, and the lamp then transferred to the exhausting pump without any air or Water vapor being occluded by the inner walls of the lamp. In all cases, however, it is found advantageous to heat the lamp as high as possible while it is on the exhausting "pump, as this heating improves the vacuum and materially shortens the time required to exhaust the bulb.

Where an inert gas is passed through the hot bulb as above described, the time required for exhausting the bulb to produce a perfect vacuum is much less than is re quired where the lamps are first heated the exhaust pump and are exhausted in the ordinary way, since there is no gradual liberation of gases and moisture from the walls of the bulb during the process of exhaustion.

My process,of, securing a vacuum may be used in exhaustingmercury lamps, rectifier tubes and all similar articles, in which a perfect and unchangeable vacuum is re many changes and modifications may be made in the Way in which the invention is carried out, I do not desire to be restricted to the precise details herein disclosed, but intend to cover. by the ap pended claims all changes and modifications within the spirit and scope of my invention.

because there my hand this and desire to secure United States, 1s,-

What I claim as new by Letters Patent of the 1. The process of freeing a glass vessel from occluded gases and moisture, which consists in heating said vessel While open to the atmosphere to a temperature at which the walls of the vessel begin to soften, washing out said vessel by passing a stream of dried gas through said vessel during the time it is above the temperature at which gases or moisture are occluded, and thereafter sealing said vessel air tight before air and moisture are again occluded.

2. The process of removing occluded gases and moisture from the walls of the bulb of an'incandescentlump, which consists in heating the lamp to about 400 degrees centigrade, passing a stream of hydrogen through said bulb while hot enough to prevent occlusion of gases or moisture, and thereafter exhausting said lamp at a temperature of about 300 degrees centigrade.-

3. The process of evacuating an incandescent lamp bulb, which consists in heating said lamp bulb while open to the atmosphere to a temperature at which the bulb begins to soften, passing a stream of dried inert gas through the bulb while hot enough to prevent ocelusion of gases or moisture, and thereafter evacuating and sealing the bulb before air or moisture is again occluded.

4. The process of producing an evacuated glass vessel free from occluded gases and moisture, which consists in heating said vessel before evacuation to a. temperature at which the walls of the vessel begin to soften, washing out said vessel by passin through it at that temperature a stream 0' dry gas, and thereafter evacuating said vessel at a lower temperature and sealin it before air or moisture is again occludec.

5. The process of producin" an evacuated glass vessel free from occluded gases and moisture, which consists in heating said vessel before evacuation to a temperature hi h enough to prevent occlusion of gas or mo1stare, freeing said vessel from gases and moisture by passing through it While so heated a stream of gas, and subsequently evacuating and sealing said vessel before gas or moisture is again occluded.

In witness whereof, I have hereunto set 25th day of November, 1908. WILLIS R. WHITNEY. Witnesses BENJAMIN B. HULL, HELEN Onronn. 

